This proposal comprises four area of research aimed at developing treatment procedures which can more effectively prevent or reverse dental caries. These different approaches share the common base of seeking a better understanding of tooth mineral-fluoride interactions and physico- chemical mechanism of the caries process. I. Improved Fluoride Rinses and Dentifrices. In a 1-minute application of a fluoride rinse or dentifrice, less than 0.3% of the fluoride is deposited on the tooth surfaces. It is proposed that an experimental system for fluoride rinses and dentifrices, which in our preliminary studies deposited up to 15 times more fluoride without increasing the fluoride concentration in the rinse or dentifrice, be investigated and developed into clinically useful formulations. II. Topical Treatments for Enamel and Root. A topical fluoride treatment developed during the reported period is capable of both depositing calcium fluoride on tooth surfaces and incorporate firmly-bound fluoride into the tooth mineral. In the proposed research this treatment will be optimized in terms of (1) maximizing firmly-bound fluoride deposition, (2) providing effective protection against lesion formation in vitro and in vivo caries challenges, and (3) being able to deliver the fluoride to those tooth sites (fissures), proximal and cervical surfaces) where the protection is needed most. III. Practical and Effective Remineralization of Enamel and Root Lesions. Two approaches, both embodying multiple short treatments with agents that are harmless even if swallowed, will be investigated under in vitro and in vivo conditions. The objective is to develop remineralization procedures that are both effective and practical. IV. Physico-chemical Models for Caries. A number of parameters associated with the tooth mineral which may decrease or increase the rate of lesion progression will be studied using a dissolution-diffusion model for caries.